Display settings: Adjust "Limit FPS" tooltip

Tooltip now mentions that the game must be restarted for the setting to
take effect. Also removed "to 100%" and "at high resolutions" as these
statements are not accurate.

data/gui/window/preferences/03_display.cfg

@@ -272,7 +272,7 @@
 			[toggle_button]
 				id = "fps_limiter"
 				label = _ "Limit FPS"
-				tooltip = _ "Disabling this increases CPU usage to 100% but may slightly improve performance at high resolutions"
+				tooltip = _ "Disabling this increases CPU usage, but may slightly improve performance (requires restart to take effect)"
 			[/toggle_button]
 		[/column]
 	[/row]